Need Help With EPI M50 Speakers

[gelid]

Re-starting a topic that I began in a thread of "Norman Nicolai" about his EPI M50 speakers. I recently found a pair of these, and returned here to learn something about them.

I found these at a local thrift store for about $16.00. They looked old, ugly as hell, and when I turned one around to check the manufacturer, I discovered they were way-heavier than they looked. Lucky for me that old, ugly, and heavy are exactly what I look for... in a mystery-to-me speaker.

Norman convinced me that I may just have something that's worth putting a bit of work into. The surrounds were in really great shape, I learned, because they are not foam, but a rubber-material.

A bit of research and I read that it was common to have the dual magnets shift over time and restrict or even prevent the movement of the cone. Sure enough, both of mine were stuck tight. After removing the woofers, I found that the magnets were visibly out of alignment, and I couldn't move the speaker cones in nor out.

I was able to shift the magnets of one into a close-to aligned state by hand and that freed up the cone a bit, but not totally.

Almost a week later I returned to the EPI's. I clamped the one I haven't messed with yet into a bench vise by the metal backing plate and tried to shift the mags around with some c-clamps. Then, I tried pulling on the basket and found that it could be spun around. Still, no movement in the cone, so I shifted it left-to-right, forward and back. no improvement. Then I pulled up on the basket and it popped off, exposing the voice coil in all its magnificent perfection. Yup, all that messing around with it, and (luckily) the basket just freely pulled off the magnet with no damage.

Short story long, can someone please tell me what I need to do next... I was not expecting the basket to just pull off like that; looks like they were glued together, but with what? Is there a better way to attach them? How do I re-assemble the basket to magnets without further risk of damage to the voice coil?

I have restored two pairs of vintage speakers (KLH Model Thirty-One and Jensen Model 2, both documented on this site) so while I have experience, I don't have a lot of it.

Any help would be greatly appreciated

Pictures:

[gelid]

I may have found something to try.

Discovered a closed thread here titled "Glued Magnet Assemblies" that asks why not bolt the mag assembly to the basket.

I thought of that myself, but it seemed too simple of a solution... an obvious thing that for reasons unknown to me just hasn't been implemented.

Well, turns out it is done on some speakers, so that is what I will do.

35+ years as a skilled machinist, I have machined all sorts of materials, but I don't recall ever drilling a magnet. I assume these on the EPI M50's are iron magnets, based on their gray color.

I do have some other stray speaker mags to practice on when I return to work later this week.

[gelid]

I have both woofers freed up and moving as they should.

I've decided to not screw the assemblies together. Rather, I'll run a thick bead of construction adhesive around the perimeter of the square plates top and bottom, to keep things from sliding around.

I do have one question: Does it matter if the magnet is flipped upside down? I'd like to know before I glue them in place. My last attempt at the alignment, I forgot to pay attention to the magnet orientation, and the face that was originally up is now down.

 

Edit: I think I now know that it does matter. Before I undo the 2 hours of careful positioning of the assembly, I need to verify for sure the polarity of the magnet and compare it to the other woofer.